This problem only seems to affect admin users.
Only affects some posts, not all posts.

A admin user will create a new topic in a category. The topic will be posted to the forum successfully. There will be no warnings/notification on the initial topic that it will be auto closed. After about 5-10 mins, The topic will show that it will be auto close after 60 mins.

I am sure that I did not set the auto close flag for this topic.
I am sure that the category does not have the “auto close after x” flag set.
I am sure that none of my other admins set this flag either.